8 HAPTER C THE INFLUENCE OF EMBRYO CULTURE MEDIUM ON NEONATAL BIRTHWEIGHT AFTER SINGLE EMBRYO TRANSFER IN IVF C.G. Vergouw E.H. Kostelijk E. Doejaaren P.G.A. Hompes C.B. Lambalk R. Schats Human Reproduction 2012; 27: 2619-2626 CHAPTER 8 ABSTRACT Study question: Does the type of medium used to culture fresh and frozen-thawed embryos influence neonatal birthweight after single embryo transfer (SET) in IVF? Summary answer: A comparison of two commercially available culture media showed no significant influence on mean birthweight and mean birthweight adjusted for gestational age, gender and parity (z-scores) of singletons born after a fresh or frozen- thawed SET. Furthermore, we show that embryo freezing and thawing may lead to a significantly higher mean birthweight. What is known and what this paper adds: Animal studies have shown that culture media constituents are responsible for changes in birthweight of offspring. In human IVF, there is still little knowledge of the effect of medium type on birthweight. Until now, only a small number of commercially available culture media have been investigated (Vitrolife, Cook® Medical and IVF online medium). Our study adds new information: it has a larger population of singleton births compared to the previously published studies, it includes outcomes of other media types (HTF and Sage®), not previously analysed, and it includes data on frozen-thawed SETs. Design: This study was a retrospective analysis of birthweights of singleton newborns after fresh (day 3) or frozen-thawed (day 5) SET cycles, using embryos cultured in either of two different types of commercially available culture media, between 2008 and 2011. Participants and setting: Before January 2009, a single-step culture medium was used: human tubal fluid (HTF) with 4 mg/ml human serum albumin (HSA). From January 2009 onwards, a commercially available sequential medium was introduced: Sage®, Quinn’s advantage protein plus medium. Singletons born after a fresh SET (99 embryos cultured in HTF and 259 in Sage®) and singletons born after a frozen-thawed SET (32 embryos cultured in HTF only, 41 in HTF and Sage® and 86 in Sage® only) were analysed. Only patients using autologous gametes without the use of a gestational carrier were considered. Also excluded were: (vanishing) twins, triplets, babies with congenital or chromosomal abnormalities and babies born before 22 weeks of gestation. Main results and the role of chance: Analysis of 358 singletons born after a fresh SET and 159 singletons born after a frozen–thawed SET showed no significant difference between the HTF and Sage® groups in terms of birthweight. Gestational age, parity and gender of the baby were significantly related to birthweight in multiple linear regression analyses, and other possible confounding factors included maternal age, BMI and smoking, the number of blastomeres of the transferred embryo and the type of culture medium. Maternal age, BMI and smoking, gestational age at birth, gender of 132 EMBRYO CULTURE MEDIUM AND NEONATAL BIRTHWEIGHT the baby and the percentage of firstborns did not differ significantly between the HTF and Sage® groups, however, among the fresh embryos, those cultured in Sage® had significantly more blastomeres at the time of embryo transfer compared to the embryos cultured in HTF. Birthweights adjusted for gestational age and gender or gestational age and parity (z-scores) were not significantly different between the HTF and Sage® groups for fresh or frozen–thawed SETs. Mean birthweight, as well as the mean birthweight among firstborns and the mean birthweights adjusted for gestational age and gender or parity (z-scores) were significantly higher in the cryopreservation group compared to the fresh embryo transfer group. Bias, confounding and other reasons for caution: Our study is limited by its retrospective design and only two commercially available culture media were tested. More research is necessary to investigate the potential influence of culture media on gene expression. Generalizability to other populations: Although our data do not indicate major influences of the HTF and Sage® culture media on birthweight, our results cannot be extrapolated to other culture media types. Furthermore, there remains a potential influence of embryo culture environment on epigenetic variation not represented by birthweight differences but by more subtle features. Study funding/competing interest(s): No external funding was obtained for this study. 8 133 CHAPTER 8 INTRODUCTION Singletons born after assisted reproductive technologies (ARTs) are at increased risk of adverse neonatal outcome, such as low birthweight and preterm delivery1-5. The origin of adverse neonatal outcomes after ART may be related to the technical procedures themselves or to patient-related factors. Several studies suggest that adverse neonatal outcomes are associated with subfertility1,6-8, while others declare no relation between subfertility and low birthweight and preterm delivery1,9. Other well-known factors that influence neonatal outcome are BMI of the mother, smoking and alcohol consumption10-12. Furthermore, increased birthweights have been linked to gender, with boys having on average higher birthweights than girls, and birthweight also increases as parity and gestational age increase13. Mean birthweight increases with an increasing average cell number in the embryo at day 3 as well14. Impacts of the IVF technology, such as ovarian stimulation (controlled ovarian hyperstimulation COH), on birthweights have also been studied. Pelinck et al.15 found a trend towards lower birthweight after ovarian stimulation while eliminating the laboratory procedures as a cause. In addition, embryo freezing and thawing does not seem to have a negative influence on the incidence of preterm delivery and low birthweight9,16,17. Another important factor, the embryo culture medium used in IVF laboratories, may have an influence on neonatal outcome, including birthweight. Animal studies have shown that culture media constituents are responsible for changes in birthweight of offspring (reviewed by Young et al.18). In human IVF, there is still little knowledge of the effect of medium type on birthweight. Studies by Dumoulin et al.19 and Nelissen et al.20 showed that the type of embryo culture medium used has a significant effect on early embryonic development, fetal development and birthweight of the baby. In contrast, Eaton et al.21 recently demonstrated no significant association between embryo culture medium and birthweight. In these studies, only a small number of the commercially available culture media were investigated: GI.3 and GI.5 medium (Vitrolife, Göteborg, Sweden); Cook® medium (Cook® Medical, Brisbane, Australia) and Global medium (IVF online, Toronto, Canada) and mainly children born after a fresh embryo transfer were included. To investigate further the influence of medium type on neonatal outcome, more commercially available media should be included in a study design. The aim of the current study was to compare birthweights of neonates after IVF treatment with a single embryo transfer (SET), where fresh and frozen-thawed embryos were cultured in one of two commercially available types of media. 134 EMBRYO CULTURE MEDIUM AND NEONATAL BIRTHWEIGHT MATERIALS AND METHODS PATIENTS The base population consisted of couples with an ongoing pregnancy after either a fresh IVF/ICSI cycle, or a frozen-thawed embryo transfer cycle at VU University Medical Center between 2008 and 2010. During this time, two different types of culture media were used, as a complete switch was instigated in January 2009. Before January 2009, a single-step commercially available culture medium was used: human tubal fluid (HTF; Lonza, Belgium) with 4 mg/ml human serum albumin (HSA; GPO, Sanquin, the Netherlands). From January 2009 onwards, a commercially available sequential medium was introduced: Sage®, Quinn’s advantage protein plus medium (CooperSurgical, USA). Embryos derived from a fresh IVF/ICSI cycle were cultured either in HTF (before January 2009) or in Sage® (after January 2009). Frozen-thawed embryos, however, could have three origins: cultured completely in HTF (freezing and thawing before January 2009, ‘HTF group’); cultured in HTF before freezing and cultured in Sage® after thawing (freezing before and thawing after January 2009, ‘HTF/Sage® group’); or cultured completely in Sage® (freezing and thawing after January 2009, ‘Sage® group’). Except for the switch in the type of embryo culture medium, no other significant changes were made in the laboratory protocols. STIMULATION PROTOCOL FRESH IVF/ICSI CYCLES Women underwent COH in a long GnRH agonist (triptoreline [Decapeptyl®; Ferring, Denmark] protocol, starting the agonist in the last week of an oral contraceptive (Microgynon® 30; Shering, Germany). For women with a previous poor response, a short GnRH agonist protocol was applied. Ovarian stimulation was performed with recombinant FSH (Gonal-F®; Merck Serono, Germany or Puregon®; MSD, USA). Cycles were monitored by transvaginal ultrasounds and serum estradiol measurements. 8 Human chorionic gonadotropin (hCG; [Pregnyl®; Organon, the Netherlands]) 10,000 IU s.c. was given 36 h before ultrasonographic-guided oocyte retrieval, when there was at least one follicle ≥18 mm and three or more follicles ≥16 mm. Luteal phase support (progesterone intravaginally; 3X200 mg daily; Utrogestan®; Besins Health care, Belgium) was started on the day of oocyte retrieval. 135 CHAPTER 8 FROZEN-THAWED EMBRYO